Characterization of Red/Green/Blue Orbital Angular Momentum Modes in Conventional G.652 Fiber
Characterization of Red/Green/Blue Orbital Angular Momentum Modes in Conventional G.652 Fiber
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DOI：
10.1109/jqe.2017.2708524
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发表时间：
2017-08
影响因子：
2.5
通讯作者：
Shi Chen;Jian Wang
中科院分区：
文献类型：
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作者：
Shi Chen;Jian Wang
光波的空间域在光通信中引起了越来越多的兴趣。具有螺旋相位波前和携带轨道角动量（OAM）的光波在自由空间和基于光纤的光通信中都有潜在的应用。广泛部署的常规ITU-T G.652光纤是1550 nm处的单模光纤，然而，其可以支持高阶模以及短波长处的OAM模。在本文中，我们提出了详细的理论分析的模式特性的圆偏振OAM模式在传统的G. 652光纤在三个RGB波长（红色在632. 8 nm，绿色在532 nm，和蓝色在476. 5 nm）。G.652光纤的纤芯半径为4.6- $\mu \text{m}$，包层半径为62.5- $\mu \text{m}$，纤芯和包层之间的折射率差为0.277%。我们首先研究所有的圆柱矢量模式（光纤本征模）和合成的圆形OAM模式通过适当的线性组合的简并光纤本征模支持在G.652光纤在三个RGB波长。然后，我们计算了有效模面积和非线性，并讨论了红色，绿色和蓝色OAM模式的光纤椭圆度和弯曲（$\text{n}_{\text {eff}$差异，$2\pi $走离长度，10 ps走离长度，损耗和OAM串扰）的公差。此外，我们还研究了常规半导体激光器的另外三个波长处的OAM模式特性，即，780、650和405 nm。此外，我们还估计了光纤衰减，传播损耗和通信带宽/容量。所获得的结果可以刺激广泛有趣的OAM相关的应用，使用传统的G.652光纤，特别是对于数百米或公里级的短距离/距离应用。
The space domain of lightwaves has attracted increasing interest in optical communications. Lightwaves having helical phase front and carrying orbital angular momentum (OAM) have seen potential applications both in free-space and fiber-based optical communications. The widely deployed conventional ITU-T G.652 fiber is single mode fiber at 1550 nm, which, however, might support high-order modes as well as OAM modes at short wavelength. In this paper, we present detailed theoretical analyses on the mode properties of circularly polarized OAM modes in conventional G.652 fiber at three RGB wavelengths (red at 632.8 nm, green at 532 nm, and blue at 476.5 nm). The G.652 fiber has a 4.6- $\mu \text{m}$ core radius, a 62.5- $\mu \text{m}$ cladding radius, and 0.277% refractive index difference between the core and the cladding. We first study all the cylindrical vector modes (fiber eigenmodes) and synthesize the circular OAM modes by proper linear combination of degenerate fiber eigenmodes supported in the G.652 fiber at three RGB wavelengths. We then calculate the effective mode area and nonlinearity and discuss the tolerance to fiber ellipticity and bending ( $\text{n}_{{\text {eff}}}$ differences, $2\pi $ walk-off length, 10-ps walk-off length, loss, and OAM crosstalks) for red, green, and blue OAM modes. Additionally, we investigate the OAM modes properties at another three wavelengths of conventional semiconductor lasers, i.e., 780, 650, and 405 nm. Moreover, we also estimate the fiber attenuation, propagation loss, and communication bandwidth/capacity. The obtained results may stimulate wide interesting OAM related applications using conventional G.652 fiber, especially for hundreds of meters or km-scale short reach/distance applications.